Many aircraft carry emergency flotation devices should they cease flying while over water. Such flotation devices may include life rafts for passengers and crew as well as floats for the aircraft itself. This is particularly true for certain helicopters flying over-water missions, which helicopters often contain both inflatable rafts and inflatable floats. Prior to deployment, the floats typically are mounted to landing skids of the helicopters, whereas the rafts normally are stowed inside the cabins.
Should a helicopter need to ditch in water, prior to ditching the pilot typically activates the inflatable floats by pulling a handle or lever mounted to a primary flight control. Actuating inflation of the life rafts may be more difficult, however. If the rafts are stowed within the aircraft cabin, their premature inflation could injure passengers or crew or interfere with crew control of the aircraft. Similarly, premature inflation of externally-stowed rafts could result in their being displaced from the aircraft or, alternatively, becoming entangled in aircraft controls. Preventing inadvertent actuation of raft inflation systems thus is of substantial importance to aircraft passengers and crew.
U.S. Pat. No. 7,314,398 to Parrott, et al. discloses certain helicopter flotation systems comprising both floats and life rafts. Indicated in the Parrott '398 patent is that “[i]nflation of the floats is achieved using . . . an actuator, such as an electrical or mechanical switch, to release a canister of compressed gas into an air hose . . . and into the floats.” See Parrott '398, col. 4, 11. 19-22 (numerals omitted). Inflation of the life rafts occurs likewise. See id., 11. 41-45. No further description of the actuator—or of preventing inadvertent actuation—occurs in the Parrott '398 patent, however.
U.S. Pat. No. 7,207,522 to Parrott, et al. discusses safety trigger devices associated with inflatable life rafts. According to the Parrott '522 patent, such devices may include multiple handles, with movement of any of the handles triggering inflation of the rafts via rotation of a cam. The handles are intended to be spaced about a helicopter so that the rafts may be inflated “from a plurality of locations including the cockpit and each side o” f the helicopter. See Parrott '522 at col. 1, 11. 36-38. Again, however, no description of preventing inadvertent actuation of inflation systems is made. Moreover, offering multiple actuation handles may increase, rather than decrease, the likelihood of premature inflation of the rafts.
An existing pneumatic actuator of the assignee of this application includes a cockpit-located handle as well as a shear, or “breakaway,” wire. Connected between the handle and the base, the breakaway wire inhibits certain inadvertent inflation actions. Until sufficient force is applied to the handle to overcome the strength of the wire, the handle remains seated in the base, preventing actuation of inflation.
Although these existing actuators of the assignee perform well, they may be subjected to instances in which crew (or passengers if in the cockpit) inadvertently apply sufficient force to the handles to break the wires. As an example of such an instance, should a strap from a camera or flight bag encircle a handle, the bag holder may attempt to detangle the strap by yanking on it. This yanking could apply momentary force to the handle greater than the strength of the breakaway wire, causing the wire to fail and the handle to extend, in turn actuating the inflation system for the raft. Need thus exists for actuators designed to diminish further the possibility of inadvertent activation by passengers or crew.